Coupler Assembly for Rotary Sensor Alignment
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Solution Overview
Problem
Mechanical hysteresis between rotating blades and sensors in grader type work vehicles affects the accuracy of rotary position systems, necessitating a coupler that minimizes this issue.
Innovation Solution
A coupler assembly with a coupler pin featuring a first part with an interference fit to the rotary unit and a second part with a key slot and cross-cuts, allowing for a slip fit and interference fit with the sensor, eliminating mechanical hysteresis by ensuring precise alignment and rotation without free-play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coupler is used to connect the rotary unit to the sensor, then the rotary position can be sensed, but mechanical hysteresis occurs between the rotating blade and the sensor which reduces measurement accuracy
Solution Approach 1:
The coupler pin is divided into multiple sections by axial cross-cuts, creating segmented sections that can flex radially. This segmentation allows the coupler to accommodate interference fit requirements while eliminating mechanical hysteresis through controlled flexibility.
Solution Approach 2:
The coupler pin utilizes different fit types (interference fit and slip fit) at different sections to change the mechanical parameters. The interference fit sections provide rigid connection for accuracy, while the slip fit section with cross-cuts provides flexibility to eliminate hysteresis.
2Manufacturing precision
If an interference fit is used to ensure precise alignment, then alignment accuracy is improved, but installation force and complexity increase
Solution Approach 1:
The coupler pin is segmented by axial cross-cuts into multiple sections. This segmentation allows the interference fit to be applied only at specific locations (base and tip) while the intermediate sections remain flexible, reducing the overall installation force required compared to a fully rigid interference fit.
Solution Approach 2:
The coupler pin transitions from a static rigid structure to a dynamic flexible structure through the cross-cuts. The flexible sections can deform radially during installation to accommodate the interference fit, then return to their original position to maintain precision alignment.
3Measurement precision
If a rigid coupler is used to eliminate free-play, then measurement accuracy is improved, but the coupler requires higher strength and may be more complex to manufacture
Solution Approach 1:
The coupler pin is divided into rigid sections (base and tip) and flexible sections (intermediate portions with cross-cuts). The rigid sections provide the necessary strength to eliminate free-play and ensure measurement accuracy, while the flexible sections reduce the overall strength requirements by allowing controlled deformation.
Solution Approach 2:
Different sections of the coupler pin have different mechanical properties: the base and tip sections have interference fits for rigidity and strength, while the intermediate sections have cross-cuts for flexibility. This local differentiation optimizes both strength and precision requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The coupler assembly achieves zero mechanical hysteresis, ensuring accurate rotary position sensing by maintaining precise alignment and rotation between the rotary unit and sensor, reducing installation force and promoting a reliable interference fit.
Implementation Method 1
The first part is coupled to the rotary unit with an interference fit, and the second part is coupled to the input member with an interference fit
Data Source
AI summary
A coupler pin couples an output sleeve of rotary unit to an input member of a rotary sensor with interference fits. The coupler pin has a first part and a second part. A key groove is formed in an inner surface of a coupling bore in the output sleeve. The first part is received by the coupling bore, and the first part has a key member which is received by the key groove. The second part has a key slot formed therein. The input member has a key. The key has a slip fit with a first part of the key slot and has an interference fit with a second part of the key slot. The key projects inwardly from a wall of a coupling bore in the input member. The second part is divided into a plurality of sections by axially extending cross-cuts.